The activity of cytosolic phospholipase A2 (cPLA2) may be altered by calcium or by phosphorylation of serines in the cPLA2 molecule. Activation of TLR4 receptors or surface receptors by sphingosine 1 phosphate may signal for phosphorylation of cPLA2. Binding of lipopolysaccharide to TLR4 results in phosphorylation of cPLA2 by MAP Kinases. This activation of MAP Kinases is mediated by both MyD88 and by TRIF activated through TLR4. Ongoing studies include the study of cPLA2 activation by lipid mediators such as sphingosine 1-phosphate. Sphingosine 1-phosphate acting through the S1P3 receptor activates cPLA2 in a time and dose dependent manner involving calcium flux, activation of MAP kinases and activation of sphingosine kinase.